The present invention relates to the field of can openers. Most household metal containers for liquid foods or chemicals require that their top be perforated by means of some type of can opener, except for those containers fitted with some built-in opening mechanism, such as a pull-tab, screw cap or friction lid.
The most commonly used implement for puncturing can tops consists of a triangular shaped cutting edge (frequently referred to as a "church key") that is levered into the metal top from the rim of the can to create one or two apertures through which the contents can be directly poured.
Convenient as it is, this mode of operation presents a dual shortcoming: on the one hand, pouring straight from the container creates a spilling hazard, and the larger the can, the greater the risk. This risk is particularly present for viscous liquids, such as cooking oils or liquid chocolate concentrate. On the other hand, because the can openings produced by conventional can openers are small and the triangular cut-out portion of the can top is folded straight down into the can, there is little possibility of developing or even adapting any appropriate sealing device to keep the can contents from evaporating or from losing their flavor. This drawback is particularly applicable to large size cans of fruit juices, evaporated milk or liquid diet foods.
Various types of sealing devices combining a spout and lid structure have been designed to fit pull-tab can openings, as described in our co-pending U.S. patent applications, Ser. Nos. 620,124 and 620,180, both filed Oct. 6, 1975. While these sealing devices can be conveniently adapted to cylindrical or oblong flat top cans to overcome the aforedescribed shortcomings, they do require a specially designed can opener capable of developing a suitably sealable opening.
Accordingly, it is the prime objective of this invention to provide an opener designed to cut in a can top a suitable perforation of generally triangular but standard shape, which can be plugged air-tight by means of a variety of specially fitting capping devices of correspondingly standard geometry.
It is another objective of this invention to provide a can opener designed to make a can opening of such characteristics that substantially flexible thermoplastic capping spouts can develop therewith a suitably tight seal and be made to pour from as well.
It is still another objective of this invention to provide a can opener of simple and safe mechanism capable of being used by people of most ages as ordinary means of creating a convenient aperture for the pouring of contents from the can.